If you cannot boil your water, mix eight drops (1/8 teaspoon) of unscented, ordinary household chlorine bleach per gallon of water. Mix the solution thoroughly, and let stand for about 30 minutes before using.
Household bleach sold for use in laundering clothes is a 3–8 of sodium hypochlorite at the time of manufacture. Strength varies from one formulation to another and gradually decreases with long storage.
The raw materials for making household bleach are chlorine, caustic soda, and water. The chlorine and caustic soda are produced by putting direct current electricity through a sodium chloride salt solution in a process called electrolysis. Sodium chloride, common table salt, comes from either mines or underground wells. The salt is dissolved in hot water to form a salt solution, which is then treated for impurities before it is reacted in the electrolytic cell.